Holder was followed by Jean Kennedy Smith, 85, the last surviving Kennedy sibling, who was accompanied by other family members to lay a wreath at her brother's grave.

"Today and in the decades to come, let us carry his [Kennedy's] legacy forward. Let us face today's tests by beckoning the spirit he embodied - that fearless, resilient, uniquely American character that has always driven our nation to defy the odds, write our own destiny, and make the world anew," said President Barack Obama.

US President John F Kennedy was shot on 22 November, 1963ReutersA silhouette of John F Kennedy Jr saluting his father's casket at the JFK Memorial PlazaReutersDealey Plaza remembersReutersCrowds gather in Dealey Plaza for commemorative ceremonies marking the 50th anniversary of JFK's assassinationReutersA video camera atop Dealey Plaza's "grassy knoll," records the crowdsReutersThe sixth floor window of the Texas Book Depository, where Lee Harvey Oswald was positioned when he shot President John F Kennedy,Reuters